Gear roll chamfering

ABSTRACT

Helical gears are rolled to improve tooth surfaces and in the same operation have the acute end corners of the teeth chamfered. The chamfering precedes finish rolling so as to avoid displacement of metal above the tooth profile.

nited States Patent [191 'Ierscl'n GEAR ROLL CHAMFERING [75] Inventor: Richard W. Tersch, Grosse Pointe Woods, Mich.

[73] Assignee: Lear Siegler, Inc., Santa Monica,

Calif.

[22] Filed: Jan. 27, 1972 [21] Appl. No.: 221,357

[52] US. Cl. ..72/98, 29/1592, 72/102,

90/1 .4 [51] Int. Cl. ..B2lh 5/00 [58] Field of Search ..72/98, 102, 109;

Primary Examiner-Lowell A. Larson Attorney-Donald P. Bush [57] ABSTRACT Helical gears are rolled to improve tooth surfaces and in the same operation have the acute end corners of the teeth chamfered. The chamfering precedes finish rolling so as to avoid displacement of metal above the tooth profile.

9 Claims, 4 Drawing Figures 1 GEAR ROLL CHAMFERING BRIEF SUMMARY OF THE INVENTION Gear rolling operations are known in which roughed out work gears are rolled in mesh with one or more gear-like dies under substantial pressure. In this operation the pressure is usually applied by effecting a relative radial depth feed between the work gear and the die or dies.

It has also been previously proposed to chamfer the ends of gear teeth in a rolling operation by applying a chamfering pressure to the acute corners of the teeth so as to displace metal beyond the original ends of the teeth. Such an operation is disclosed in Paulger U.S.

Pat. No. 3,233,5 l 8, in which the chamfering operation is independent of a gear rolling operation and in which the displaced metal is shaved away from the ends of the teeth.

In accordance with the present invention a gear rolling apparatus is provided, preferably employing a single gear-like die, in which means are provided for effecting relative radial or depth feed between the die and the gear in order to establish rolling pressure between the teeth of the die and the gear. In addition, means are provided for effecting a relative traverse between the die and gear in a plane parallel to the axes of both the die and gear. Conveniently, this relative traverse may be in a direction parallel to the axisof the gear.

Associated with the die, which is generally conjugate to the desired form of teeth on the work gear, are a pair of chamfering dies the profile curvature of the teeth being the same as that of the gear rolling die but the teeth being tapered, or having one side inclined as in Paulger U.S. Pat. No. 3,233,518, so that as the work gear is moved axially to force the ends of its teeth into the tapered tooth spaces of the chamfering die, the

. acute corners are chamfered. In order to provide the essential pressure for this chamfering operation, preferably the tooth surfaces of the chamfering dies adjacent the obtuse corners are continuations of the sides of the teeth of the rolling die.

Obviously, as an alternative, the taper may be differently arranged so that if desired, the obtuse corners might be chamfered, or in some cases, a spur gear could be provided with a mild chamfer at all four corners of each tooth thereof.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevational view of a machine employed in practice of the present invention.

FIG. 2 is an enlarged view of the assembly of rolling and tapered dies.

FIG. 3 is a fragmentary elevational view on the line 3-3, FIG. 2. FIG. 4 is a much enlarged composite showing of the die assembly showing its operation on adjacent teeth of a work gear.

DETAILED DESCRIPTION Referring now to FIG. 1 there is shown a gear rolling machine comprising a frame having a forwardly-projecting portion 12 carrying a rotatable gear rolling. die 14. Suitable means (not shown) are provided for driving the die in rotation.

At the lower end of the frame 10 there is a forwardly projecting base portion 16 carrying a support 22 which is vertically adjustable by threaded adjusting means indicated generally at 24. Mounted for vertical movement on the frame is a slide 26 which is connected to the support 22 by toggle mechanism indicated generally at 28 and adapted to be rocked by suitable means such for example as a hydraulic piston and cylinder device diagrammatically indicated at 30, to bring the intermediate pivot 32 of the toggle device into vertical alignment with a lower pivot 34 provided on the upper end of the support 22, and an upper pivot 36 provided at the interior of the vertically movable slide 26.

The vertically movable slide 26 carries a sub-table 40, herein shown as angularly adjustable about a vertical axis and provided at its upper end with rectilinear ways indicated at 42, which carries an upper table 44 for horizontal movement along the ways 42. Means are provided for effecting horizontal traverse of the upper table 44 and this means is indicated as a nut 46 carried by the sub-table 40, and a feed screw 48 carried by the upper table 44 and in threaded engagement with the nut. Suitable means such as a worm 50 and worm gear 52 are provided for effecting rotation of the feed screw, the worm 50 being driven by a motor indicated at 54 carried by a bracket 56 mounted on the upper table 44. In the embodiment of the invention illustrated, a crowning table 60 is mounted on a pivot connection 62 intermediate the upper table 44 and the crowning table 60, and suitable cam means (not shown) may be provided for effecting rocking of the crowning table 60 in accordance with traverse thereof as effected by the feed screw 48. Alternatively, suitable means may be provided for rocking the crowning table 60 without traverse of the upper table 44 to accomplish substantially horizontal movement of a work gear W, as will subsequently be described.

If the crowning table is not to be rocked, suitable adjustable abutment means (not shown) are provided in- .termediate the crowning table and the upper table 44.

Mounted on the crowning table 60 between stocks 64 is the work gear W, which is in mesh with the rolling die 14.

In conventional single roll roll finishing, the assembly of tables and the work gear are moved vertically as the gear W and die 14 are driven in rotation, as for example, by movement of the toggle device 28. Gear forming pressure is applied between the toothed surfaces of the teeth of the die 14 and the gear W.

In accordance with the present invention, instead of employing a single gear-like die 14, a die assembly as best illustrated in FIG. 2 is provided. In this assembly the die support arbor is indicated at and includes an intermediate enlarged portion on which is provided an adapter 72 having a cylindrical flange 74 at one end. The adapter 72 is keyed to the arbor 70 by the key 76.

Engaging the opposite sides of the gear rolling die 14 are chamfering dies 80. Each chamfering die includes a toothed portion 82 and a reduced cylindrical portion 84. As will subsequently be described, the teeth of the chamfering dies are in substantial alignment with the teeth of the gear rolling die but are tapered in such a way as to engage end surfaces of the teeth of a work gear moved axially to bring the ends of its teeth into the converging tooth spaces of the chamfering dies.

Since the rolling action of the dies and gear is accomplished by driving the die or die assembly in rotation, it will be understood that the arbor 70 is driven and accordingly, the adapter 72 is driven in rotation. Suitable means such for example as a pin 86, is provided to couple the flange 74 of the adapter to the left hand chamfering die 80 as seen in FIG. 2. Rotation of the left hand chamfering die is transmitted to the gear rolling die by means of circumferential adjusting and driving means including a pin 90, details of which are best illustrated in FIG. 3, in conjunction with FIG. 2. Referring to these Figures, the pin 90 extends through an opening in the gear rolling die 14 and into enlarged openings 92 in the chamfering dies 80. Adjustment screws 94 are provided in openings 96 in the chamfering dies. As one of the screws 94 is retracted the other may be advanced to effect angular adjustment between the chamfering dies and the gear rolling die. In addition to providing for angular adjustment, it will of course be apparent that the pin 90 and the screws 94 constitute driving connections so that the left hand chamfering die 80 drives the rolling die 14, which in turn drives the right hand chamfering die 80, as seen in FIG. 2.

As shown in the enlarged fragmentary sectional view of FIG. 4, the teeth of the gear rolling die 14 are indicated at 100 and the teeth of the chamfering dies 80 are indicated at 102. The tooth surfaces 104 of the gear rolling die are longitudinally concave so that in the final rolling operation the teeth of the gear may be longitudinally convex or crowned, although this is not a part of the present invention. Portions of the gear teeth cooperating with the die teeth 100 and 102 are indicated at 106 and 108, and in FIG. 4 it will be observed that the teeth of the gear are helical and that the end corners of the teeth at one side of the gear are obtuse as indicated at 110 while the other end corners 112 of the teeth at the same side are acute.

It is desired to provide means for chamfering the acute corners of the gear teeth to provide the chamfered surfaces thereof as indicated at 114. In order to accomplish this the teeth of the chamfering die are provided with surfaces 116 which are continuations of the surfaces 104 of the teeth of the gear die except of course for the special concavity of these teeth indicated at 104, which may or may not be provided. In other words, the surfaces 116 of the teeth 102 of the chamfering die are shown as extending at the same helix angle as the teeth of the gear W. On the other hand, the teeth 102 are tapered so that the opposite side of the teeth of the chamfering die as indicated at 118, extend at an angle to the sides 116, and in FIG. 4 the surfaces 118 are indicated as extending generally parallel to the axes of the gear and dies, or perpendicular to the planes thereof. In other words, the surfaces 118 may be considered as surfaces of a conventional spur gear tooth.

With this arrangement the spaces 120 between adjacent teeth 102 of the chamfering dies are tapered.

It will be appreciated that with this arrangement if the work gear W is moved into a position of substantially full mesh with the teeth of the rolling die 14, with however slight clearance or backlash between the teeth, and if at this time, while the die assembly and gear are rotated in mesh, the gear is traversed axially as by rotation of the feed screw 48, the ends of the teeth of the work gear will be forced to enter into convergingly tapered spaces 120 between adjacent teeth of the chamfering die. In FIG. 4 the parts are illustrated in the position occupied when the teeth 108 and of the gear G have been forced into the tooth spaces of the chamfering die 80 at the right of the Figure. The

surfaces 116 of the teeth of the chamfering die engage in proper meshing relation with the sides 122 of the gear teeth but the acute angled corner of the gear teeth, and particularly the tooth 108 as viewed in this Figure, is forced into chamfering engagement with the straight side 118 of the teeth of the chamfering die. Accordingly, the chamfered surface 1 14 is produced and some material, as indicated at 124, is displaced beyond the end of the gear teeth.

It will be understood that after the acute angled end corners of the teeth at one side of the gear G are chamfered, as indicated in FIG. 4, the direction of traverse of the gear is reversed, and the gear is moved to the left as seen in FIG. 4. This movement continues until the acute angled corners 112 at the opposite side of the gear are chamfered as previously described. Thereafter, the gear is again traversed in reverse direction until it occupies the plane of the rolling die 14 and is out of registration with both of the chamfering dies.

The chamfering operation while it is effective to produce the chamfered surface 114 and to displace material beyond the ends of the teeth as indicated at 124, may in some cases displace a minor amount of metal into the operating surface of the tooth.

In accordance with the present invention, any protuberance thus caused of material beyond the desired tooth profile is eliminated by the subsequent rolling operation in which the work gear is fed into the die until the tooth surfaces are roll finished, as is well understood in the art.

It is pointed out that during the final roll finishing of the sides of the teeth, it is not practical to provide the chamfered surfaces simultaneously with production of the roll finished surfaces, because of possible interference which would produce minor imperfections in the accuracy of the tooth profile. It is accordingly essential in the present method that the gear teeth be chamfered first, followed by radial depth feed to produce the required surface finish and dimensioning of the teeth of the gear.

Reference was made to the possibility of employing the rocking table 60 as means for effecting substantially axial movement of the gear W into engagement with the chamfering dies. This will eliminate the necessity of providing the feed screw 48 and associated mechanism. Minor rocking movement of the crowning table 60 from the intermediate horizontal position will be sufficient to bring the ends of the teeth of the gear into engagement with the tapered chamfering dies, particularly if the width of the gear rolling die is only slightly greater than the width of the gear.

The method may be carried out with the work gear in tight mesh with the tooth rolling die, and this tends to minimize displacement of material above the profiled surface of teeth, or the chamfering operation may be carried out with the gear and tooth rolling die in mesh but with appreciable back-lash or clearance.

What I claim as my invention is:

1. The method of roll finishing and chamfering gears which comprises providing a die assembly of a gear rolling die having teeth substantially conjugate to the desired form to be produced on the teeth of a work gear, and achamfering die directly adjacent one side of the rolling 'die and having teeth in end alignment with and forming continuations of the teeth of the rolling die, one side of the chamfering teeth being angularly disposed to the corresponding side of the teeth of the gear rolling die to intercept the adjacent corners of gear teeth, meshing the teeth of the gear with the teeth of the rolling die near to at least substantially full depth, driving the die assembly and gear in rotation, relatively traversing the gear and die assembly in a plane parallel to the axes of both to force the ends of the teeth at one side of the gear into the tooth spaces of the chamfering die to chamfer end corners thereof, reversing traverse to bring the teeth of the gear into registration only with the teeth of the rolling die, providing a relatively depth feed between the gear and die assembly to roll finish the teeth of the gear from end to end and to roll out any protuberance in the gear teeth surfaces caused by the roll chamfering, and finally separating the gear and die assembly.

2. The method as defined in claim 1 in which the teeth of the chamfering die are tapered.

3. The methodas defined in claim 1 in which the gear is helical, and the tooth taper on the chamfering die provides a chamfering surface engageable with the gear teeth only at the acute angled corner side.

4. The method as defined in claim 1 which comprises providing a chamfering die as aforesaid at both sides of the rolling die, continuing reverse traverse to chamfer the end corners at the gear teeth at the other side of the gear.

5. The method as defined in claim 3 which comprises providing a chamfering die as aforesaid at both sides of the rolling die, continuing reverse traverse to chamfer the end corners at the gear teeth at the other side of the gear.

6. The method as defined in claim 3 in which the tooth surfaces at one side of the teeth of the chamfering die form smooth continuations of the corresponding sides of the teeth of the rolling die to back up the sides of the gear teeth at one side thereof as the end corners at the opposite side are chamfered.

7. The method as defined in claim 1 in which relative traverse between the gear and die assembly is substantially parallel to the axis of the gear.

8. The method as defined in claim 7 in which the relative traverse is accompanied by axial movement of the gear relative to the die assembly.

9. The method as defined in claim 7 in which the relative traverse between the gear and die assembly is accomplished by rocking the gear about an axis perpendicular to its own axis and disposed at the opposite side of the gear from that portion thereof in meshing engagement with the die assembly. 

1. The method of roll finishing and chamfering gears which comprises providing a die assembly of a gear rolling die having teeth substantially conjugate to the desired form to be produced on the teeth of a work gear, and a chamfering die directly adjacent one side of the rolling die and having teeth in end alignment with and forming continuations of the teeth of the rolling die, one side of the chamfering teeth being angularly disposed to the corresponding side of the teeth of the gear rolling die to intercept the adjacent corners of gear teeth, meshing the teeth of the gear with the teeth of the rolling die near to at least substantially full depth, driving the die assembly and gear in rotation, relatively traversing the gear and die assembly in a plane parallel to the axes of both to force the ends of the teeth at one side of the gear into the tooth spaces of the chamfering die to chamfer end corners thereof, reversing traverse to bring the teeth of the gear into registration only with the teeth of the rolling die, providing a relative depth feed between the gear and die assembly to roll finish the teeth of the gear from end to end and to roll out any protuberance in the gear teeth surfaces caused by the roll chamfering, and finally separating the gear and die assembly.
 2. The method as defined in claim 1 in which the teeth of the chamfering die are tapered.
 3. The method as defined in claim 1 in which the gear is helical, and the tooth taper on the chamfering die provides a chamfering surface engageable with the gear teeth only at the acute angled corner side.
 4. The method as defined in claim 1 which comprises providing a chamfering die as aforesaid at both sides of the rolling die, continuing reverse traverse to chamfer the end corners at the gear teeth at the other side of the gear.
 5. The method as defined in claim 3 which comprises providing a chamfering die as aforesaid at both sides of the rolling die, continuing reverse traverse to chamfer the end corners at the gear teeth at the other side of the gear.
 6. The method as defined in claIm 3 in which the tooth surfaces at one side of the teeth of the chamfering die form smooth continuations of the corresponding sides of the teeth of the rolling die to back up the sides of the gear teeth at one side thereof as the end corners at the opposite side are chamfered.
 7. The method as defined in claim 1 in which relative traverse between the gear and die assembly is substantially parallel to the axis of the gear.
 8. The method as defined in claim 7 in which the relative traverse is accomplished by axial movement of the gear relative to the die assembly.
 9. The method as defined in claim 7 in which the relative traverse between the gear and die assembly is accomplished by rocking the gear about an axis perpendicular to its own axis and disposed at the opposite side of the gear from that portion thereof in meshing engagement with the die assembly. 